Storage tanks for fuel, oil, propane, natural gas, and other liquid materials are typically cylindrical or spherical. Since the majority of these storage tanks are made of ferrous materials, a magnet mounting base is one choice for making a semi-permanent attachment to the tank, i.e., an attachment that is stably and securely mounted but that can be easily detached, if desired. However, the curved or rounded external shape of the tank does not lend itself to the attachment of the flat magnet mounting bases known in the art, as, for example, described in U.S. Pat. No. 3,206,905 to Wavering et al. and U.S. Pat. No. 5,585,809 to Yajima et al., the disclosures of which are fully incorporated herein by reference. Also, in another example of a magnet mounting base with a flat planar contact edge on its base, U.S. Pat. No. 5,405,004 to Vest et al., the disclosure of which is fully incorporated herein by reference, describes a cup style magnet for use in attaching a tray to a metal surface where a magnet is disposed within a cup-shaped ferromagnetic support having a cylindrical side wall that terminates at a generally circular and planar support rim. U.S. Pat. No. 5,699,910 to Kubat describes a pair of pivotal magnet assemblies to couple a tray to a non-flat surface.
One approach for magnet mounting bases is the use of magnet support legs, as for example described in U.S. Pat. No. 4,363,402 to Grzyll, to prevent a receptacle from moving when placed on an inclined surface. Another approach for magnet mounting bases is the use of spaced apart magnet bars and a support ring disposed between the bars, as for example described in U.S. Statutory Invention Registration No. H865 to Sery et al. for attaching a torch to a flat, curved, or irregular magnetic surface.
An easily detachable magnet mounting base that fastens securely and stably to a rounded magnetic surface without the complexity of additional movable parts, such as pivotal components, or without the complexity of fabricating multiple permanent magnets as bars or legs into a mounting base, would be advantageous for reliable and economical attachment of various devices to rounded surfaces, such as to the typically cylindrical or spherical exterior surfaces of storage tanks.